Sprint Nextel Corp raised its buyout offer for wireless service provider Clearwire Corp to $3.40 per share on Tuesday under pressure from activist shareholders, but the new bid failed to impress several big investors.

Clearwire shares traded around the new offer price after Sprint was forced to revise its original $2.97 per share offer just hours before a scheduled shareholder vote on the deal.

Analysts and investors had predicted that the original bid would not have won approval. Clearwire said it would review the new bid and postponed the vote to May 30.

However, the improved offer met with an icy reception from several investors including several top-20 Clearwire shareholders with more than 14 percent of the minority votes.

Crest Financial, the biggest of the opposing minority shareholders with about 8 percent of Clearwire's public shares, urged Clearwire shareholders and its board to reject the new offer which it said "significantly undervalues Clearwire."

Crest, which had led a proxy fight against the original deal, said it would make sense for Clearwire to await the outcome of an ongoing takeover battle between Dish Network Corp and Japan's SoftBank Corp <9984.T> to buy Sprint before pursuing competitive acquisition offers for Clearwire.

"Clearwire is the prize, and Sprint is trying to buy Clearwire on the cheap and lock-up Clearwire's value before Sprint itself is purchased by SoftBank or DISH," said Crest. "That lock-up is patently unfair to minority stockholders. You can and must refuse to abet Sprint in its ongoing scheme."

A money manager at a top 15 Clearwire shareholder agreed, saying the new offer "woefully undervalued" Clearwire and suggested that an offer price of $4.50 per share would have been acceptable. The person, who asked not to be named due to a lack of authorization to speak to the media, predicted that the offer would fail.

Sprint, which is looking to gain control of Clearwire's wireless airwaves to help it compete better against larger rivals, said its revised bid values Clearwire at $10.7 billion and represented its "best and final" offer.

But if this is the case an unimpressed money manager at a top-20 investor plans to keep their minority stake.

"It's not going to get my vote," said the money manager. "I guess Clearwire isn't as important to them as it is to me. We'll be fine being a minority shareholder. They should have come with a real bid or not come at all."

An analyst at another big Clearwire shareholder had been hoping for an increase to a range of $3.70 to $3.80 per share. The analyst, who asked not to be named, said approval for the new price could be "doable" but said "the odds are not great."

However, Clearwire shares, which had consistently traded above Sprint's previous offer for months, suggested a lack of investor confidence Sprint would raise its bid further.

Clearwire shares closed 4.3 percent higher at $3.40 on Tuesday, in line with Sprint's revised offer.

The fate of the new offer may hinge on the reaction of another group of four shareholders with roughly 17 percent of the minority vote. The group - Mount Kellett Capital Management LP, Highside Capital Management, Glenview Capital Management and Chesapeake Partners Management - had not commented on Sprint's bid by late afternoon.

MIXED OPINIONS

Any Clearwire deal would be contingent on the closing of Sprint's proposed plan to sell 70 percent of Sprint to SoftBank Corp for $20.1 billion. Sprint, which received approval from SoftBank to raise its bid, is currently reviewing a $25.5 billion counter offer from Dish Chairman Charlie Ergen.

SoftBank declined to comment.

A source familiar with the situation said that move would not require additional capital from SoftBank as Sprint will fund the price increase itself.

SoftBank would have been comfortable just owning a bigger majority stake in Clearwire but the source said that "Sprint made a strong case for completing the full transaction" and SoftBank wanted to be a good partner to Sprint.

Sprint said that Clearwire has received commitments from Comcast Corp , Intel Corp and Bright House Networks, who own about 26 percent of Clearwire`s minority shares, to vote for the transaction.

Analyst opinion was mixed on whether Sprint would garner enough support from the rest of the minority shareholders, even with the revised bid.

"It's a good first step but this sweetened offer I believe will be insufficient to secure a successful transaction," said Roe Equity Research analyst Kevin Roe.

But analyst Jennifer Fritzsche of Wells Fargo expects Sprint to gain support for the new offer even though she thinks some shareholders will still object.

Taran Asset Management principal Chris Gleason said he would not vote for a $3.40-per-share offer and was still hoping for a price range of $5 to $7 per share.

"We know the value is higher," said Gleason, whose firm holds more than 1 million Clearwire shares.

Investors with roughly 31 percent of the public shares had said either in statements or in interviews with Reuters that they were unhappy with the original offer.

(Additional reporting by Liana B. Baker in New York and Reiji Murai in Tokyo.; writing by Ben Berkowitz; editing by Gerald E. McCormick, Nick Zieminski and Matthew Lewis)